hello this is my opinion
Should we spend billions on exploring space?
Already nations, especially developed nations, have made a large investment of their public budgets, aimed at outer space research, from there we can see how they send different teams as technicians, for space exploration. As to whether the question is directed to personal spending, it is always interesting to have the opportunity to know and have new scientific references, this investment can only be made by those who have the economic capacity to do so. But I believe that in each of the countries, developed or not, it is necessary to look at the people who need food, clothing, housing, education, transport and respect for human dignity, and to make major investments in them, since in my opinion it is not worth making major investments in space exploration, if there are people in the world dying of hunger.
Good or bad?
This will depend on the interest of governments and how much social investment is being lost, to invest in space exploration...

Is the knowledge we gain worth the money we spend?
If this knowledge first responds to your concerns and is beneficial to humanity, the money invested in it will be very well spent.
What are your thoughts?
As you can see from the above answers, I agree with this investment, provided that the priorities of human attention, the enjoyment of all rights for all and the pursuit of positive happiness are not neglected, and that this acquired knowledge is used to improve man's life.